SU1160896A1 - Material for manufacturing thim-film interconnecting of integrated circuits - Google Patents

Description

evenness of the microrelief of the film surface (width at the base of 0.6 microns and height of 0.2-0.3 microns), comparable to the thickness of the interlayer dielectric (0.3-0.4 microns), make it difficult to use aluminum films containing silicon additives , with multilevel wiring of an IC interconnect due to failures caused by the destruction of the interlevel dielectric by irregularities of the film surface microrelief and short circuits between the conductive layers.

The closest technical solution is an aluminum-based thin-film IC-based interconnect material that contains a rare earth metal (RMS) or a mixture of rare earth metals.

The advantages of such a material for the manufacture of IC interconnects are the high resistance of thin films made of it to failures caused by mass transfer under the action of electric current and corrosion, high weldability by aluminum and gold wire. High degree of discreteness of films, the average grain size at the content, for example. But in the amount of 0.7 wt.% It is 0.1-0.15 µm, retaining during heat treatment at a temperature of-475-500 ° C, it allows to form IC interconnects with a minimum width of 0.5-2.0 µm .

The disadvantages of the material for the manufacture of thin-film X IC interconnects based on aluminum with the addition of rare earth metals is that the transition contact resistance (Rx) of thin aluminum films containing -lx to ringtones of rare earth metals is 25-35% higher than R, c , gtenok aluminum to silicon n-tmpa, and 35-40% higher than the RK aluminum films containing silicon additives.

The purpose of the invention is to improve the electrophysical properties of thin-film interconnects of IC and semiconductor devices mainly with small p-junctions and micron and submicron dimensions of elements while maintaining high resistance to failures caused by mass transfer under the action of electric current and corrosion, high quality micro-welding of aluminum and gold wires.

The goal is achieved by the fact that the material for the manufacture of thin-walled IC interconnects based on aluminum, containing a rare-earth metal and / or a mixture of rare-earth metals, also contains silicon with the following content of components, May,%:

Rare earth

metals and / or mixtures

rare earth

Metals0.01-4.0

Silicon0,1-2,0

Aluminum Else

The quantitative composition of the components included in this material is determined by their influence on the grain size of the thin film obtained from this material, the transitional contact resistance to silicon, the surface relief of the film.

The lower boundary of the ingredients included in this material determines the maximum impurity content, at which the effect of reducing the contact resistance of the thin film is observed and the necessary requirements for grain size and surface microrelief are preserved.

0 (see table 1, in which examples of boundary and optimal amounts of ingredients are given) and high resistance to failures due to mass transfer under the action of electric current and corrosion, high quality micro welding with aluminum and gold wires. Increased resistance to failures caused by mass transfer under the action of electric current

Corrosion, as well as the quality of ultrasonic micro-welding, is achieved by introducing impurities of rare-earth metals into the film. The upper limit determines the maximum content of impurity etto, at which there is also a decrease

5 RK while maintaining the other properties above.

The material is obtained in the usual way of melting aluminum, silicon, rare-earth metals and / or mixtures of rare-earth metals in an arc furnace, for example, brand

0 L-200 with a non-consumable tungsten electrode on a water-cooled copper tray in an inert gas atmosphere. The mixing of the alloy is carried out in this case by means of an arc. The melting conditions are as follows: the pressure of the gels in the furnace is 400 mm Hg, the current is 1200-1600 A at a voltage of 30-40 V. The re-melting time is 3-5 minutes. For a more uniform distribution of rare-earth metals and SI, each ingot is melted 3-4

Oh times. Then, homogenizing annealing of ingots was performed in air for 3–4 h at 450 ° C. The ingots had a diameter of 100 mm and a height of 8 mm. From these ingots were prepared m-target for

5 magnetron sputter material. To do this, they were machined on a lathe at a processing speed of 63 rpm. This eliminated the use of cooled emulsions. After processing on a lathe, the targets had

Dimensions: diameter 95-0.5 mm, thickness 5.5 mm.

Before being placed into the device for magnetron sputtering, the obtained targets were processed in a polishing solution of the following composition: NZRO - 16 parts, HNOZ - 1 part, CH2COOH - 1 part, H20 - 2 parts for 3-5 minutes, at a temperature of 30-40 C. Condition The production of thin films by magnetron sputtering of a target with a diameter of 95 mm and a thickness of 5 mm is as follows: the target current is 1.0-1.5 A, it’s 520-5BO B, the argon pressure in the chamber is 1.3 mm Hg, the temperature of the silicon substrate was equal to 170 ° C. The film deposition rate under these conditions was 0.02-0.04 µm / s. Under the same conditions, both aluminum (grade A99) and materials for the manufacture of interconnects based on aluminum with additives of rare-earth metals and S1 were sprayed.

The results of comparative tests are presented in table. 2 When determining the contact resistance, the resistance of the chain of 18 contacts was measured on the test element. The n-region doping dose was 700 µC. From table 2 it follows that the proposed material has a lower contact resistance to silicon than the known materials, while maintaining high resistance to failures caused by mass transfer under the action of electric current. Evaluation of the value of the normal electrode potential in a solution of ethylene glycol aluminum films with additives of rare-earth metals and SI showed that it is less negative than for aluminum, as well as aluminum alloys with SI additives, and in order of magnitude is comparable to the normal electrode potential of aluminum with additives of rare-earth metals 0.48 In (see tab.2). This allows us to conclude about the high corrosion resistance of thin-film IC interconnects based on the proposed material.

Materials based on aluminum and other rare-earth metals containing silicon were also obtained. Used Y: Yb; Xie; Nd and other rare-earth metals. The results of the study of RK, average grain size, surface microrelief and other properties are slightly different from those presented in Tables 1 and 2. Mischmetall — a mixture of rare-earth metals containing Ce — 45–50; Nd - 18; Pr 5: Sm - 1; La - 20-25; the rest: impurities Y, Eu, Tb and other rare-earth metals, i and A1; Co; Ca; Mp; SI; N1; RY: Fe; C. Results are similar. In particular, the Republic of Kazakhstan is 250-300 ohms. The surface microrelief, the average grain size of the films, the mean time to failure, the normal electrode potential — all of these characteristics are slightly different in magnitude from those obtained on AI + Ho + SI; AI + Tb + Sl; AI + Eu + St.

. Thus, this material for the manufacture of thin-film IC interconnects, used for semiconductor devices, has significant advantages over the known ones: in terms of the asperities of the surface relief of films obtained by spraying, and a more uniform distribution of grains resistance to silicon. At the same time, the high resistance of thin-film conductors of this material to failures caused by mass transfer under the action of electric current and corrosion, as well as high quality of aluminum and gold wire micro welding, is maintained.

The material can also be used in the manufacture of interconnects MOS-integrated circuits with small p-n-re-. strokes and multilevel wiring system, for example, in the manufacture of microcircuits for electronic watches, as well as microcircuits for other purposes.

The dependence of the contact resistance and grain size on the composition of the materialTable 1 rial

Claims (1)

(54X57) MATERIAL FOR MANUFACTURING THIN FILM INTERCONNECTIONS OF INTEGRAL MICROCIRCUITS (IMS) based on aluminum, containing a rare-earth metal and / or a mixture of rare-earth metals, characterized in that. in order to improve the electrophysical properties of thin-film IC interconnects while maintaining high failure resistance, it additionally contains silicon in the following components, wt.%: Rare earth metal and / or mixtures rare earth of metals 0.01-4.0 Silicon 0.1-2.0 Aluminum Rest